Avatar tracking and rendering in virtual reality

Abstract

Virtual Reality systems may be used in healthcare and therapy, e.g., focusing on physical and neurorehabilitation. For instance, victims of brain injury may seek treatment to improve, e.g., range of motion, balance, coordination, joint mobility, flexibility, posture, endurance, and strength. VR systems can be used to entertain and instruct patients in their movements while recreating practical exercises to further therapeutic goals. Patient movement data during physical therapy sessions may be valuable to patients and healthcare practitioners. The system may comprise a plurality of body sensors, a VR headset, and a supervisor tablet. The disclosed system may facilitate translation between real world coordinates and virtual world coordinates, assigning sensors to body parts, measuring range of motion of joints and limbs, correcting sensor orientation, recording and presenting therapy data, and generating and animating a 3-D virtual reality avatar in a virtual world to perform activities, among other benefits.

1 . A virtual reality system, the system comprising:
 a plurality of sensors comprising a first sensor and a second sensor, the first sensor with a first relative position and the second sensor with a second relative position;   a head-mounted display (HMD) in communication with the plurality of sensors, wherein the HMD is distanced from the first sensor by a first offset; and   processing circuitry configured to:
 generate a virtual coordinate system comprising a first virtual position and a head virtual position based on the first offset; 
 map the first virtual position to the first relative position; and 
 determine a second virtual position in the virtual coordinate system based on the first virtual position, the first relative position, and the second relative position. 
   
     
     
         2 . The system of  claim 1 , wherein each of the plurality of sensors has a corresponding relative sensor position and each is configured to wirelessly transmit the corresponding relative sensor position. 
     
     
         3 . The system of  claim 1 , wherein the processing circuitry further configured to determine, for each of the plurality of sensors, a respective virtual position based on each corresponding relative sensor position, the first virtual position, and the first relative position. 
     
     
         4 . The system of  claim 1 , wherein each of the plurality of sensors is configured to transmit the corresponding relative sensor position via radio frequency. 
     
     
         5 . The system of  claim 1 , wherein each corresponding relative sensor position comprises a position and orientation. 
     
     
         6 . The system of  claim 1 , wherein the first sensor is fixed to the HMD. 
     
     
         7 . The system of  claim 1 , wherein a wireless transmitter module (WTM) comprises the second sensor. 
     
     
         8 . A method of determining virtual reality world coordinates from relative physical positions of sensors placed on a body, the method comprising:
 receiving, by a wireless receiver, a plurality of sensor positions communicated from each of a plurality of sensors placed on the body, the plurality of sensors including a first sensor in spaced relation by a physical offset to a head-mounted display (HMD) and a second sensor;   accessing virtual world coordinates for a virtual world position of the HMD;   determining a virtual world position of the first sensor based on the physical offset and the virtual world position of the HMD;   determining a relative physical position of the second sensor in relation to the first sensor;   determining virtual world position of the second sensor based on the relative physical position of the second sensor and the virtual world position of the first sensor; and   determining a virtual world position for each remaining sensor of the plurality of sensors based on the virtual world position of the second sensor and a relative physical position of each of the plurality of sensors to the second sensor.   
     
     
         9 . The method of  claim 8 , wherein the plurality of sensors further comprises two hand sensors, two elbow sensors, and a hip sensor. 
     
     
         10 . The method of  claim 8 , wherein the receiving is performed wirelessly via radio frequency. 
     
     
         11 . The method of  claim 8 , the method further comprising transmitting to a therapist device at least one virtual world position corresponding to one of the plurality of sensors. 
     
     
         12 . A method of assigning sensors placed on a body, the method comprising:
 receiving, by a wireless receiver, a plurality of sensor positions communicated from each of a plurality of sensors placed on the body, each of the plurality of sensor positions comprising a height and a hemisphere;   identifying a wireless transmitter module (WTM) sensor of the plurality of sensors placed on the body;   identifying a head sensor of the plurality of sensors based on one of the received plurality of sensor positions being most high;   comparing the position of each of the plurality of sensors to the position of the WTM sensor; and   identifying each of the plurality of sensors based on the position of each of the plurality of sensors in relation to the WTM sensor.   
     
     
         13 . The method of  claim 12 , wherein identifying remaining sensors comprises identifying remaining sensors based on sensor positions indicating a left hemisphere or a right hemisphere. 
     
     
         14 . The method of  claim 12 , wherein identifying remaining sensors comprises identifying an elbow sensor based on a similar height to the WTM sensor. 
     
     
         15 . The method of  claim 12 , wherein identifying remaining sensors includes identifying a hip sensor and two hand sensors based on a similar height to each of the hip sensor and hand sensors. 
     
     
         16 . The method of  claim 12 , wherein identifying remaining sensors includes identifying ankle sensors based on the position of the ankle sensors being lowest. 
     
     
         17 . The method of  claim 12 , wherein the receiving is performed wirelessly via radio frequency. 
     
     
         18 . A method of automatically correcting sensor orientation, the method comprising:
 receiving a plurality of sensor data communicated from each of a plurality of sensors placed on the body;   generating an avatar skeleton based on the sensor data;   determining an angle for a joint of the avatar skeleton;   comparing the angle of the joint to a predetermined threshold;   in response to determining the angle of the joint is greater than the predetermined threshold, inverting a yaw axis for a corresponding one of the plurality of sensors.   
     
     
         19 . The method of  claim 18 , wherein the joint is a wrist. 
     
     
         20 . The method of  claim 19 , wherein the predetermined threshold is between 50 and 60 degrees. 
     
     
         21 . The method of  claim 18 , wherein the joint is an elbow. 
     
     
         22 . The method of  claim 21 , wherein the predetermined threshold is between 170 and 190 degrees. 
     
     
         23 . The method of  claim 18 , wherein the joint is a hip. 
     
     
         24 . The method of  claim 23 , wherein the predetermined threshold is between 45 and 60 degrees. 
     
     
         25 .- 51 . (canceled)